package org.apache.lucene.index;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.document.Document;
import org.apache.lucene.document.FieldSelector;
import org.apache.lucene.store.Directory;

import java.io.IOException;
import java.util.Collection;

/**
 * A <code>FilterIndexReader</code> contains another IndexReader, which it
 * uses as its basic source of data, possibly transforming the data along the
 * way or providing additional functionality. The class
 * <code>FilterIndexReader</code> itself simply implements all abstract
 * methods of <code>IndexReader</code> with versions that pass all requests to
 * the contained index reader. Subclasses of <code>FilterIndexReader</code>
 * may further override some of these methods and may also provide additional
 * methods and fields.
 */
public class FilterIndexReader extends IndexReader {

	/** Base class for filtering {@link TermDocs} implementations. */
	public static class FilterTermDocs implements TermDocs {
		protected TermDocs in;

		public FilterTermDocs(TermDocs in) {
			this.in = in;
		}

		public void seek(Term term) throws IOException {
			in.seek(term);
		}

		public void seek(TermEnum termEnum) throws IOException {
			in.seek(termEnum);
		}

		public int doc() {
			return in.doc();
		}

		public int freq() {
			return in.freq();
		}

		public boolean next() throws IOException {
			return in.next();
		}

		public int read(int[] docs, int[] freqs) throws IOException {
			return in.read(docs, freqs);
		}

		public boolean skipTo(int i) throws IOException {
			return in.skipTo(i);
		}

		public void close() throws IOException {
			in.close();
		}
	}

	/** Base class for filtering {@link TermPositions} implementations. */
	public static class FilterTermPositions extends FilterTermDocs implements
			TermPositions {

		public FilterTermPositions(TermPositions in) {
			super(in);
		}

		public int nextPosition() throws IOException {
			return ((TermPositions) this.in).nextPosition();
		}

		public int getPayloadLength() {
			return ((TermPositions) this.in).getPayloadLength();
		}

		public byte[] getPayload(byte[] data, int offset) throws IOException {
			return ((TermPositions) this.in).getPayload(data, offset);
		}

		// TODO: Remove warning after API has been finalized
		public boolean isPayloadAvailable() {
			return ((TermPositions) this.in).isPayloadAvailable();
		}
	}

	/** Base class for filtering {@link TermEnum} implementations. */
	public static class FilterTermEnum extends TermEnum {
		protected TermEnum in;

		public FilterTermEnum(TermEnum in) {
			this.in = in;
		}

		public boolean next() throws IOException {
			return in.next();
		}

		public Term term() {
			return in.term();
		}

		public int docFreq() {
			return in.docFreq();
		}

		public void close() throws IOException {
			in.close();
		}
	}

	protected IndexReader in;

	/**
	 * <p>
	 * Construct a FilterIndexReader based on the specified base reader.
	 * Directory locking for delete, undeleteAll, and setNorm operations is left
	 * to the base reader.
	 * </p>
	 * <p>
	 * Note that base reader is closed if this FilterIndexReader is closed.
	 * </p>
	 * 
	 * @param in
	 *            specified base reader.
	 */
	public FilterIndexReader(IndexReader in) {
		super();
		this.in = in;
	}

	public Directory directory() {
		return in.directory();
	}

	public TermFreqVector[] getTermFreqVectors(int docNumber)
			throws IOException {
		ensureOpen();
		return in.getTermFreqVectors(docNumber);
	}

	public TermFreqVector getTermFreqVector(int docNumber, String field)
			throws IOException {
		ensureOpen();
		return in.getTermFreqVector(docNumber, field);
	}

	public void getTermFreqVector(int docNumber, String field,
			TermVectorMapper mapper) throws IOException {
		ensureOpen();
		in.getTermFreqVector(docNumber, field, mapper);

	}

	public void getTermFreqVector(int docNumber, TermVectorMapper mapper)
			throws IOException {
		ensureOpen();
		in.getTermFreqVector(docNumber, mapper);
	}

	public int numDocs() {
		// Don't call ensureOpen() here (it could affect performance)
		return in.numDocs();
	}

	public int maxDoc() {
		// Don't call ensureOpen() here (it could affect performance)
		return in.maxDoc();
	}

	public Document document(int n, FieldSelector fieldSelector)
			throws CorruptIndexException, IOException {
		ensureOpen();
		return in.document(n, fieldSelector);
	}

	public boolean isDeleted(int n) {
		// Don't call ensureOpen() here (it could affect performance)
		return in.isDeleted(n);
	}

	public boolean hasDeletions() {
		// Don't call ensureOpen() here (it could affect performance)
		return in.hasDeletions();
	}

	protected void doUndeleteAll() throws CorruptIndexException, IOException {
		in.undeleteAll();
	}

	public boolean hasNorms(String field) throws IOException {
		ensureOpen();
		return in.hasNorms(field);
	}

	public byte[] norms(String f) throws IOException {
		ensureOpen();
		return in.norms(f);
	}

	public void norms(String f, byte[] bytes, int offset) throws IOException {
		ensureOpen();
		in.norms(f, bytes, offset);
	}

	protected void doSetNorm(int d, String f, byte b)
			throws CorruptIndexException, IOException {
		in.setNorm(d, f, b);
	}

	public TermEnum terms() throws IOException {
		ensureOpen();
		return in.terms();
	}

	public TermEnum terms(Term t) throws IOException {
		ensureOpen();
		return in.terms(t);
	}

	public int docFreq(Term t) throws IOException {
		ensureOpen();
		return in.docFreq(t);
	}

	public TermDocs termDocs() throws IOException {
		ensureOpen();
		return in.termDocs();
	}

	public TermPositions termPositions() throws IOException {
		ensureOpen();
		return in.termPositions();
	}

	protected void doDelete(int n) throws CorruptIndexException, IOException {
		in.deleteDocument(n);
	}

	protected void doCommit() throws IOException {
		in.commit();
	}

	protected void doClose() throws IOException {
		in.close();
	}

	public Collection getFieldNames(IndexReader.FieldOption fieldNames) {
		ensureOpen();
		return in.getFieldNames(fieldNames);
	}

	public long getVersion() {
		ensureOpen();
		return in.getVersion();
	}

	public boolean isCurrent() throws CorruptIndexException, IOException {
		ensureOpen();
		return in.isCurrent();
	}

	public boolean isOptimized() {
		ensureOpen();
		return in.isOptimized();
	}
}
